Seamanship - World of Wave Craft

[jon hansen]

i'm just a messenger. been sailing sailboats 58 yrs. drove great lakes ships 18 yrs. love the thrill of sailing just like you guys all do. read hundreds of books on sailing. looking to improve my skills.
high performance sailing by frank bethwaite is 100 times better book on sailing than all the others combined.
the first half of this large book is about how the wind move across the surface of the earth. the wind at the boat, 100 ft out, one mile out, 5 mile out, 50 mile out, 200 mi out, etc.... winds near lands of many shapes.
he talks of how to read the signs, and how to sail the wind. how to put your self in the best winds for your needs.
you win races by putting your boat in stronger winds for a longer duration. than your competitor and you win every time. no longer do you have to whine about ratings. the wind, how it really works, is a rarely discussed issue at races. there is no thread on this web site talking about wind. yet,its understanding is number one it to performance of these toys we all enjoy.
every issue on sailing these toys asked on this web sight is answered in his book.
jackdaw and a number of others try and share this type of knowledge. thats great. and welcome. there are some skilled, thought full sailors on this sight for sure.

hulls, foils, rigs, sails, wind, water, waves, tuning, shaping, deploying, retrieving, preparing, driving, weighting, then after all that a good discussion on the class room is over and your driving the boat and the complexities of this moving toy all coming into harmony.
then you find out what frank and his kids and friends have achieved in this life.

 

[jon hansen]

its an easy read. you can refer back to it easily.

 

[jon hansen]

capta, the worst ride on the water in any size vessel ever for me was in the same area as you mentioned. 54' cutter private boat in top shape. billionaire owner, with all the toys in triplicate. the owner, supper nice never pushed us, just wanted the crew and the vessel to be safe. i was a watch captain. the capt is life long friend of great skill. we had sailed up from the caribbean . we were at grand bahama waiting on weather. headed to charleston next. love the mega dock. then north. the boat was going to maine for the season. we used commanders out of new hampshire for our weather service. a tropical low, first of that year, was north of us over water and forecast to drift s by sw and move over florida around jacksonville then weaken over land.
so our plan was to wait for landfall of the low and jump out into the gulf stream and blast north with current and reaching winds. we understood that some left over waves from the north would be there but hoped that they would knock down in short time. so we departed the bahamas motored out to the stream. swung north. put out full sail and away we go. that day we had the old swell on the nose with the wind at a tight reach. the low wobbled. i never heard of that. just like a dying top on the kitchen floor. it wobbled. it touched the fla coast then shot due east across our bow and went 100 east of us and stayed there. we had huge swells from many directions all at some angle against the stream. breaking waves, from all over, piggy backing waves. tropical storm winds. all sail down, of course. way to chaotic to even consider the auto pilot. either at the helm or in my bunk it was brace brace brace. bailed out with a course to st augustine. very weird motion with no consistency. way uncomfortable. we stayed in st augustine for three days to heal.

capta, you are correct in saying that by then it is nice to be on a vessel you can trust.

 

[dlochner]

Thermoclines occur when water stratifies based on temperature and density of the water. Water at the bottom of a deep lake or ocean is always at 39* F because that is the temperature at which water reaches its maximum density. Between 32 and 39 degrees water becomes less dense until it forms ice which floats to the top. Likewise, water that is warmer than 39 is also less dense and tends to rise.

Another factor is the ability of the sun to warm the water. At some depth sunlight no longer penetrates and water is no longer warmed by the sun. The water then stratifies into different layers based on temperature and density. The boundary between these layers is a thermocline.

Thermoclines can be both horizontal and vertical. When a vertical thermocline forms the rising water brings more nutrients up from deeper waters. On Lake Ontario, it is easy to find the thermocline, there will be a line of boats fishing. There is also a noticeable difference in air and water temperature as one sails across the thermocline.

 

[Will Gilmore]

Just came across this short Smithsonian article on waves. Considering some of the fascinating posts in this thread, I thought it worth posting. Currents, Waves, and Tides: The Ocean in Motion

Some of the waves written about in the article exceed 50' in height. A question that comes to mind is, how does a sailor best negotiate large waves? I use to believe driving straight into oncoming waves was best. This is a practice I learned navigating small boats across wakes in bays or on lakes. Rolling over a broaching wave just kills. Since then, I have come to feel that angling up and over a large wave is both more comfortable and allows for maintaining better control. The vessel's stern doesn't come put of the water as you crest the wave, the diagonal angle is stable and headway may be easier to maintain because the climb up the wave is less steep. These are just my sense of reason, no factual knowledge other a small amount of anecdotal ocean experience.

-Will (Dragonfly)

 

[PaulK]

Many of the big waves that get written up are swells, not cresting waves. Boats simply float on top as the water level beneath them rises and falls, almost like a tide, but quicker. Nice view from the top, less from the trough. Angling up & down steeper waves works well until they start cresting. Then you need to try to pick your path as best you can. Biggest cresting waves we’ve had to deal with were in gales, about 20’ high.

 

[Will Gilmore]

Reviving an old thread here to post this article about a recent rogue wave event of Vancouver.
The Most Extreme 'Rogue Wave' on Record Was Just Confirmed in The North Pacific

 

[jssailem]

Oh great...
Just when I am talking about planning for a cruise along the Western coast of Vancouver Island, you have to dredge up the 2018 Rogue Wave conspiracy... the Ucluelet wave.

That is such a quiet and peaceful Sound. Maybe we can engage in the grooming tips for Sasquatch as well.

Waves 58 ft tall. That is the stuff that keeps sailors up at night drinking rum.

 

[Will Gilmore]

Is not the height that is the problem. It's like falling from an airplane. You're fine until that sudden stop at the end.
Boats don't care how tall the wave is, they care how steep, and how much curl falls into their boats. One could make pretty good headway surfing down a wave like that.

-Will

 

[jssailem]

Or roll over repeatedly taking one on the beam.
Worse would be surfing down the face into the bottom of the trough. It is not the surfing find a concern, It is driving into the wall of water at the bottom of the trough. It is worse than concrete.

 

[Will Gilmore]

It is worth understanding the need to not take big waves, up or down, straight on or at right angles. I do the same with driving over steep bumps and troughs in the road. Take them at an angle.

-Will

 

[jon hansen]

'love machine' 1976 sorc pj built

 

[Will Gilmore]

The definition of a rogue wave is a wave that is more than twice the height of the surrounding waves.

That looks like a rogue wave, Jon.

-Will

 

[jon hansen]

 

[Will Gilmore]

There is not a lot of water under that keel.

-Will

 

[jssailem]

There’s a lot of water over that bow.

 

[jssailem]

I saw this image today and shuddered. The waves were not enough, there has to be lightening too.

 

[dmdiehl64]

Thanks for reviving this thread, what a gem. As a dinghy racer on the Huron bay and starting this year, cruising Lake Huron, very good information especially thermocline. I'd heard of the lake turning over twice a year but never took enough time to understand the thermodynamics behind it.

Also, Frank Bethwaite just sold another book! Looking forward to learning a bit from "High Performance Sailing".

 

[jssailem]

WOW... is that book just getting to Michigan? published in 2011.

A great book. Will teach you skills to be quick about your sailing trim. I encourage you to read it.

 

[jon hansen]

..... and it will teach one how to drive a sailing vessel over the surface of the water while teaching the best place to play while understanding the weather